With the continuous development of display technology, flat display devices have become able to achieve various display functions, such as, dual viewing field display, anti-spy display, 3D display, etc.
Dual viewing field display refers to such a display technology that different images can be seen on two different sides (e.g., left and right sides) of the same display device. For the existing dual viewing field display technology, a dual viewing field display is realized mainly in such a way that a grating is disposed in front of a display screen, and light-transmissive regions and light-shading regions that are arranged alternately on the grating are utilized for separating light for displaying to both sides of the display screen, so as to make observers on both sides see different pixels.
In the anti-spy display technology, by means of arranging a grating in front of a display screen, the normal display region can be only confined to a narrower region having frontal viewing angles. Only within a certain view-angle range (for example, the viewing angle is smaller than 60 degrees), a normally displayed image can be watched by an observer, and once the viewing angle exceeds this range (for example, the viewing angle is larger than 60 degrees), the observed image becomes an all-black picture. This technology has a certain role in protecting privacy.